If you subscribe to the signal and you want to increase lot size so use the following information (this question was asked many times on the forum so I am just providing the links only) -
How to Select a Deal Volume https://www.mql5.com/en/forum/9950/page93#comment_4052813 https://www.mql5.com/en/forum/215636
How to change the volume/lot size (many posts)https://www.mql5.com/en/forum/11714
There aren't any micro lots and there isn't any normal method in order to increase the lot size of a signal's orders.
Its also highly unadvisable to do so, because you are interfering with the risk/money management of the signal provider.